NAADP-regulated two-pore channels drive phagocytosis through endo-lysosomal Ca2+ nanodomains, calcineurin and dynamin.

Macrophages clear pathogens by phagocytosis and lysosomes that fuse with phagosomes are traditionally regarded as to a source of membranes and luminal degradative enzymes. Here, we reveal that endo-lysosomes act as platforms for a new phagocytic signalling pathway in which FcγR activation recruits the second messenger NAADP and thereby promotes the opening of Ca2+ -permeable two-pore channels (TPCs). Remarkably, phagocytosis is driven by these local endo-lysosomal Ca2+ nanodomains rather than global cytoplasmic or ER Ca2+ signals. Motile endolysosomes contact nascent phagosomes to promote phagocytosis, whereas endo-lysosome immobilization prevents it. We show that TPC-released Ca2+ rapidly activates calcineurin, which in turn dephosphorylates and activates the GTPase dynamin-2. Finally, we find that different endo-lysosomal Ca2+ channels play diverse roles, with TPCs providing a universal phagocytic signal for a wide range of particles and TRPML1 being only required for phagocytosis of large targets.

Association between breakfast skipping and psychosomatic symptoms among Canadian adolescents.

This cross-sectional study aimed to examine the mediating roles of gender and substance use in the influence of breakfast skipping on psychosomatic symptoms. The study used data among a nationally-representative sample of 2855 Canadian adolescents who participated in the 2018 Health Behavior in School-aged Children (HBSC) survey. Sequential logistic regressions were used to estimate the associations between breakfast skipping and psychosomatic symptoms. Path analysis using a non-parametric bootstrapping technique tested the hypothesized mediating roles. Results showed that adolescents who skipped breakfast were 2.55 times more likely to report higher psychosomatic symptoms compared to non-breakfast skippers (AOR = 2.55; 95% CI = 1.75-3.82). The bootstrapping mediation models showed that breakfast skipping indirectly influenced psychosomatic symptoms through substance use and gender, accounting for 18.47% ( ß = 0.0052, Boots 95% CI = 0.0025, 0.00730) and 10.70% ( ß = 0.0091, Boots 95% CI = 0.0052, 0.0125), respectively, of the total effect. Our findings have important implications for targeted public and mental health interventions to address both breakfast skipping and psychosomatic symptoms among adolescents.  Conclusion: The study compellingly underscores the significance of incorporating gender-specific factors and substance use in understanding the correlation between breakfast skipping and psychosomatic symptoms. These insights hold importance for tailoring public health interventions to alleviate the prevalence of psychosomatic symptoms among adolescents by actively addressing breakfast skipping. What is Known: • Breakfast is considered the most important meal of the day due to its role in providing the brain with the energy necessary to enhance cognitive functions. • Adolescents commonly exhibit a prevalent lifestyle behaviour of skipping breakfast. What is New: • This study provides robust evidence supporting the association between breakfast skipping and elevated psychosomatic symptoms in adolescents. • Gender and substance use mediate this association, offering novel insights into the complex interplay that contributes to psychosomatic symptoms among this demographic group. • Longitudinal research is needed to unravel causal relationships and illuminate the underlying mechanisms of this intricate connection.

Lysosomal agents inhibit store-operated Ca2+ entry.

Pharmacological manipulation of lysosome membrane integrity or ionic movements is a key strategy for probing lysosomal involvement in cellular processes. However, we have found an unexpected inhibition of store-operated Ca2+ entry (SOCE) by these agents. Dipeptides [glycyl-L-phenylalanine 2-naphthylamide (GPN) and L-leucyl-L-leucine methyl ester] that are inducers of lysosomal membrane permeabilization (LMP) uncoupled endoplasmic reticulum Ca2+-store depletion from SOCE by interfering with Stim1 oligomerization and/or Stim1 activation of Orai. Similarly, the K+/H+ ionophore, nigericin, that rapidly elevates lysosomal pH, also inhibited SOCE in a Stim1-dependent manner. In contrast, other strategies for manipulating lysosomes (bafilomycin A1, lysosomal re-positioning) had no effect upon SOCE. Finally, the effects of GPN on SOCE and Stim1 was reversed by a dynamin inhibitor, dynasore. Our data show that lysosomal agents not only release Ca2+ from stores but also uncouple this release from the normal recruitment of Ca2+ influx.

NAADP-Mediated Ca2+ Signalling.

The discovery of NAADP-evoked Ca2+ release in sea urchin eggs and then as a ubiquitous Ca2+ mobilizing messenger has introduced several novel paradigms to our understanding of Ca2+ signalling, not least in providing a link between cell stimulation and Ca2+ release from lysosomes and other acidic Ca2+ storage organelles. In addition, the hallmark concentration-response relationship of NAADP-mediated Ca2+ release, shaped by striking activation/desensitization mechanisms, influences its actions as an intracellular messenger. There has been recent progress in our understanding of the molecular mechanisms underlying NAADP-evoked Ca2+ release, such as the identification of the endo-lysosomal two-pore channel family of cation channels (TPCs) as their principal target and the identity of NAADP-binding proteins that complex with them. The NAADP/TPC signalling axis has gained recent prominence in pathophysiology for their roles in such disease processes as neurodegeneration, tumorigenesis and cellular viral entry.

Staying in or out? COVID-19-induced healthcare utilization avoidance and associated socio-demographic factors in rural India.

BACKGROUND: Although evidence on healthcare utilization avoidance during COVID-19 pandemic is emerging, such knowledge is limited in rural settings. An effective policy to the COVID-19 shocks and stresses in rural settings require empirical evidence to inform the design of health policies and programmes. To help overcome this evidence gap and also contribute to policy decisions, this study aimed at examining COVID-19-induced healthcare utilization avoidance and associated factors in rural India. METHODS: This study used the third-round data from the COVID-19-Related Shocks in Rural India survey conducted between 20-24 September, 2020 across six states. The outcome variable considered in this study was COVID-19-induced healthcare utilization avoidance. Multivariable Binary Logistic Regression Model via Multiple Imputation was used to assess the factors influencing COVID-19-induced healthcare utilization avoidance. RESULTS: Data on 4,682 respondents were used in the study. Of this, the prevalence of COVID-19-induced healthcare utilization avoidance was 15.5% in rural India across the six states. After adjusting for relevant covariates, participants from the Bihar State have significantly higher likelihood of COVID-19-induced healthcare utilization avoidance compared to those from the Andhra Pradesh. Also, participants whose educational level exceeds high school, those who use government hospital/clinic, engage in daily wage labour in agriculture have significantly higher odds of COVID-19-induced healthcare utilization avoidance compared to their counterparts. CONCLUSION: Our study revealed that state of residence, type of health facility used, primary work activity and educational level were associated with COVID-19-induced healthcare utilization avoidance in rural India. The findings suggest that policy makers and public health authorities need to formulate policies and design interventions that acknowledge socioeconomic and demographic factors that influence healthcare use avoidance.

Determinants of national health insurance enrolment among people at risk of statelessness in the Awutu Senya East Municipality and Gomoa East District of Ghana.

BACKGROUND: This paper investigates the factors influencing the decision to enrol in Ghana's National Health Insurance Scheme (NHIS) among people at risk of statelessness, with emphasis on the individual's demographic and socioeconomic factors.  METHODS: The study used data from a cross-sectional household survey undertaken in the Awutu Senya East Municipality and Gomoa East District of Ghana's Central Region between March 9 and June 26, 2021, on healthcare utilization culture among people at risk of statelessness. Descriptive statistics and binary logistic regression were used in analysing data from a sample of 384 people at risk of statelessness.  RESULTS: The results reveal that about 51% of the at-risk population have ever enrolled while 48% of the respondents were enrolled on the NHIS at the time of the survey (active members). The majority of the enrolled members acquired their membership through self-payment of the enrolment fee. Additionally, respondents aged 26-35 had higher odds of enrolling, whiles those within 56-65 years had lower odds of enrolling in health insurance. Also, persons who are married and have a high school education or an equivalent qualification were more likely to enrol, while persons with no employment were less likely to enrol. CONCLUSION: According to the paper, while the gap in coverage between rich and poor, married and single appears to have narrowed, these factors continue to determine NHIS coverage among people at risk of statelessness. The same is true for education. Efforts must be increased to ensure equal access to healthcare financing interventions for better access to health services.

Self-reported symptoms of ocular allergy and its comorbid factors among residents living near a landfill site in Ghana.

Residents close to landfill sites may be exposed to long-term emitted toxic compounds that may have effects on their eyes. The aim of this study was to determine the prevalence of symptomatic ocular allergy and its comorbid factors among residents living near a landfill site in Ghana. An exploratory cross-sectional design involving 400 inhabitants living around a landfill site was employed. The prevalence of symptomatic ocular allergy was 59.3%. In a bivariate analysis, comorbid conditions including respiratory disease, coughing, flu, cholera, skin disease, diarrhoea, and hypertension predicted symptomatic ocular allergy. However, only cholera remained a significant predictor of symptomatic ocular allergy in the multivariate analysis. Symptomatic ocular allergy was high among inhabitants around the landfill site in Ghana. While proper design and management of landfills in Ghana is crucial, further longitudinal and clinical studies are required to clinically establish the link between landfill and ocular allergy.

Is illegal mining socio-politically entrenched? An opinion piece of the interaction between formal politics and chief dominance in mineral governance, and its influence on fighting Galamsey in Ghana.

Gold mining has been the backbone of Ghana's development since pre-colonial times. It has been essential in revenue mobilisation and the provision of employment to many people. However, in recent times the sector has received severe public backlash due to its inability to effect appropriate socioeconomic change; and the consequential destruction to forests, croplands and water bodies that has accompanied the livelihood activity. While the need to curb this menace has been hyper-crucial in recent times, these attempts have failed cyclically. This paper argues that the deep-seated linkages between different power actors such as politicians and chiefs/kings are the driving forces thwarting the fight against the menace. Recently, constructive criticisms from the public have rejuvenated the fight against galamsey, however, the modalities of the fight and socio-political power relations have jointly militated against the effectiveness of the fight. It is particularly argued that policymakers should rather take advantage of the evolved nature of the political landscape of Ghana, where politicians sometimes negotiate with chiefs/kings for political expediency during elections. This can be achieved by motivating chiefs/king's to become principal "galamsey-fighters". In the meantime, the authors also suggest that the confiscated excavators from the mining sites which are usually burnt should be stopped and rather sold to generate capital for reclaiming the lands.

Two-pore channels: going with the flows.

In recent years, our understanding of the structure, mechanisms and functions of the endo-lysosomal TPC (two-pore channel) family have grown apace. Gated by the second messengers, NAADP and PI(3,5)P2, TPCs are an integral part of fundamental signal-transduction pathways, but their array and plasticity of cation conductances (Na+, Ca2+, H+) allow them to variously signal electrically, osmotically or chemically. Their relative tissue- and organelle-selective distribution, together with agonist-selective ion permeabilities provides a rich palette from which extracellular stimuli can choose. TPCs are emerging as mediators of immunity, cancer, metabolism, viral infectivity and neurodegeneration as this short review attests.

[Husbands' involvement in antenatal-related care in the Bosomtwe District of Ghana: inquiry into the facilitators and barriers]. / Implication des maris dans les soins anténatals: enquête sur les facilitateurs et les barrières: Cas des habitants de Bosomtwe au Ghana.

BACKGROUND: This paper explored the facilitators and barriers to husbands' involvement in antenatal-related care in the Bosomtwe District of Ghana from the perspectives of husbands, pregnant women with and without delivery experience, nursing mothers, midwives and traditional birth attendants. METHODS: The study relied on the qualitative research design to collect and analyse data on the facilitators and barriers to husbands' involvement in antenatal-related care. The unit of analysis was made up of 36 participants-husbands (14), pregnant women with delivery experience and, nursing mothers (8), pregnant women without delivery experience (6), male and female midwives (6) and traditional birth attendants (2) who were purposively selected. The study's data was gathered using in-depth interviews and analysed through the content approach. RESULTS: Various economic [work and time constraint], cultural [the association of childbearing and its allied duties to women] and health-system factors [lack of antenatal services targeted at husbands and health professionals' attitude] hinder husbands' active participation in antenatal care. Despite these, some husbands participated in antenatal care owing to the importance they accord to the health and safety of their wives and the foetus; changing gender roles and preferential treatments received by their wives at antenatal clinics [as a result of the involvement of their husbands in prenatal care]. CONCLUSION: The implementation of alternative strategies, like, couple counselling, prolonging operating times of health centres to accommodate working men are recommended to provide a more accommodative and attractive avenue for husbands to support their wives during pregnancy. These efforts must be reinforced by the entire society through modifying the "ill-held view" that pregnancy and childcare is the sole duty of a woman.

The involvement of males [husbands] in antenatal-related care is noted to have significant impacts on the wellbeing of pregnant women and lessen burden of pregnancy, delivery and childcare. In this study, we examined the opinions of some stakeholders in the space of pregnancy and childcare [husbands, pregnant women with delivery experience, nursing mothers, midwives and traditional birth attendants], regarding the involvement of husbands in antenatal-related care. The study was conducted in the Bosomtwe District of Ghana, West Africa.The participants were asked to narrate experiences of husbands' involvement in pregnancy-related care, in addition to the barriers and facilitators of such engagement processes. A total of 36 participants were involved in the study. The narrative approach was used to report the findings.It was found that male's involvement in antenatal-related care is minimal in the study area. Factors such as limited time due to economic activities and the responsibility of providing financial resources for the wellbeing of the family and cultural factors in the form of childbearing being a responsibility of women deterred husbands from antenatal-related care. Again, absence of services that target males also served as a barrier. That notwithstanding, the importance attached by husbands to the health and safety of their wives and the foetus, the changing gender roles and preferential treatments given to pregnant women who are accompanied by their husbands facilitated males involvement.In conclusion, the study has implications for male-friendly antenatal care services development and continuous effort to undo the "cultural-ills" of male's involvement in pregnancy care in Ghana.

COVID-19 and social distancing measures in Queensland, Australia, are associated with short-term decreases in recorded violent crime.

Objectives: The objective of this study is to test whether recorded rates of violent crime declined in the context of social distancing regulations in Queensland, Australia. Methods: ARIMA modeling was used to compute 6-month-ahead forecasts of rates for common assault, serious assault, sexual offenses, and breaches of domestic violence orders. These forecasts (and their 95% confidence intervals) are compared to the observed data for March and April 2020. Results: By the end of April, 2020, rates of common, serious, and sexual assault had declined to their lowest level in a number of years. For serious assault and sexual assault, the decline was beyond statistical expectations. The rate at which domestic violence orders were breached remained unchanged. Conclusions: Social distancing regulations are temporally correlated with reductions in some violent crimes. Social distancing is likely to have significantly limited interpersonal interaction, especially in locations and at times when violence is usually prevalent.

Lessening barriers to healthcare in rural Ghana: providers and users' perspectives on the role of mHealth technology. A qualitative exploration.

BACKGROUND: Key barriers to healthcare use in rural Ghana include those of economic, social, cultural and institutional. Amid this, though rarely recognised in Ghanaian healthcare settings, mHealth technology has emerged as a viable tool for lessening most healthcare barriers in rural areas due to the high mobile phone penetration and possession rate. This qualitative study provides an exploratory assessment of the role of mHealth in reducing healthcare barriers in rural areas from the perspective of healthcare users and providers. METHOD: Semi-structured interviews were conducted with 30 conveniently selected healthcare users and 15 purposively selected healthcare providers within the Birim South District in the Eastern Region of Ghana between June 2017 and April 2018. Data were thematically analysed and normative standpoints of participants were presented as quotations. RESULTS: The main findings were that all the healthcare users had functioning mobile phones, however, their knowledge and awareness about mHealth was low. Meanwhile, rural health care users and providers were willing to use mHealth services involving phone call in the future as they perceived the technology to play an important role in lessening healthcare barriers. Nevertheless, factors such as illiteracy, language barrier, trust, quality of care, and mobile network connectivity were perceived as barriers associated with using mHealth in rural Ghana. CONCLUSION: The support for mHealth service is an opportunity for the development of synergistic relationship between health policy planners and mobile network companies in Ghana to design efficient communication and connectivity networks, accessible, localised, user-friendly and cost-effective mobile phone-based health programmes to assist in reducing healthcare barriers in rural Ghana.

Expression of Ca²âº-permeable two-pore channels rescues NAADP signalling in TPC-deficient cells.

The second messenger NAADP triggers Ca(2+) release from endo-lysosomes. Although two-pore channels (TPCs) have been proposed to be regulated by NAADP, recent studies have challenged this. By generating the first mouse line with demonstrable absence of both Tpcn1 and Tpcn2 expression (Tpcn1/2(-/-)), we show that the loss of endogenous TPCs abolished NAADP-dependent Ca(2+) responses as assessed by single-cell Ca(2+) imaging or patch-clamp of single endo-lysosomes. In contrast, currents stimulated by PI(3,5)P2 were only partially dependent on TPCs. In Tpcn1/2(-/-) cells, NAADP sensitivity was restored by re-expressing wild-type TPCs, but not by mutant versions with impaired Ca(2+)-permeability, nor by TRPML1. Another mouse line formerly reported as TPC-null likely expresses truncated TPCs, but we now show that these truncated proteins still support NAADP-induced Ca(2+) release. High-affinity [(32)P]NAADP binding still occurs in Tpcn1/2(-/-) tissue, suggesting that NAADP regulation is conferred by an accessory protein. Altogether, our data establish TPCs as Ca(2+)-permeable channels indispensable for NAADP signalling.

Exploring the Sexual Development Experiences of Black Bisexual Male Adolescents Over Time.

Scant research has sought to explore the development of dimensions of sexual orientation among Black bisexual male adolescents (BBMA). Understanding how sexual attractions, behaviors, and identities evolve among BBMA over time is crucial to understanding the most appropriate support strategies to provide during this developmental period. We sought to understand and describe the sexual orientation development experiences in a sample of BBMA over the course of 1 year. We further sought to understand the sociocontextual factors that may play a role during this development process. Fifteen BBMA, aged 15-19 years, were interviewed about sexual debut experiences (baseline) and were re-interviewed three times over a 1-year period about sexual attractions, behaviors, and identity at each follow-up point. A three-person team used inductive open coding to analyze each participant's data set. The mean Kinsey scale score for the sample was 2.93 (SD = 1.2) most closely translating to "heterosexual/gay-equally." A case study analysis was used to identify themes related to sexual attractions, behavior, and identity over time, within and across participants. Among the sample of young men, two unique groups were identified based on self-reported sexual identity and experiences of same- and other-sex sexual attractions and behaviors over time. The first group consisted of seven young men who consistently described their sexual identity as bisexual from baseline to the final follow-up. These young men also described similar experiences related to same- and other-sex sexual and romantic attractions and more consistently described same- and other-sex sexual behaviors. The second group consisted of eight young men that described changing sexual identity and same- and other-sex sexual romantic attractions over time. Participants described sociocontextual factors such as religion, masculinity, and homophobia played during their development. Findings from this study underscore the complexity of sexual orientation development and sociocultural factors and expectations that may influence sexual identity and behavior among BBMA.

Satisfaction and Condomless Anal Sex at Sexual Debut and Sexual Risk Among Young Black Same-Sex Attracted Men.

First sex may be a sentinel event crucial to understanding sexual health trajectories of young Black same-sex attracted men (YBSSAM). We sought to understand whether satisfaction, condomless anal sex, and contextual factors during first sex were associated with sexual risk and recent condom use in YBSSAM. A total of 201 YBSSAM aged 15-24 years completed an Internet survey exploring first sex, current condom use, and sexual risk. High risk was defined as ≥3 of the following: new/concurrent sex partners, STI history, and no/inconsistent condom use. Multivariate logistic regression assessed the association between predictor (satisfaction and first condomless anal sex) and outcome (sexual risk and condomless sex in the past 3 months) variables. Mean age at first sex was 15.2 (SD = 2.9) years, and emotional satisfaction (51.7 %), physical satisfaction (63.7 %), and condomless first anal sex (55.2 %) were common. YBSSAM describing high levels of satisfaction were no more likely to be at high risk or engage in recent condomless sex. Condomless first sex (AOR = 4.57, p = .001), younger age (AOR = 3.43, p = .02), and having a partner >5 years older (AOR = 2.78, p = .03) at first sex were significantly associated with increased risk. Only condomless first sex (AOR = 4.28, p < .001) was associated with condomless recent sex. Satisfaction at first sex may not influence later sexual risk in YBSSAM. However, context of first sex, including condom use at first sex, may play an important role in subsequent risk. Prevention strategies on condom negotiation prior to first sex may help to mitigate HIV burden in YBSSAM.

Sexual Health Research With Young Black Men Who Have Sex With Men: Experiences of Benefits and Harms.

Young Black men who have sex with men (YBMSM) are often underrepresented in sexual health research because of concerns about safety, privacy, and the potential for research harms. Empirical data are needed to understand YBMSM experience of participating in research, benefits and harms (discomfort), to inform policy and regulatory decisions. Using qualitative methods, this article examines 50 YBMSM, aged 15-19 years, experiences of benefits/harms, challenges of participating in sexual health research, and contextual factors impacting research experiences. Participants were asked about benefits and harms experienced in answering questions about sexual orientation, first same-sex attraction, and same-sex sexual experiences after completing an in-depth interview. Interviews were transcribed and coded. Inductive open coding was used to identify themes within and between interviews. Participants were able to describe perceived direct benefits resulting from research interview participation, including awareness of risky sexual behaviors, a safe space to share early coming out stories and same-sex sexual experiences, and a sense of empowerment and comfort with one's sexual orientation. Indirect benefits described by participants included perceptions of helping others and the larger gay community. Few participants described harms (discomfort recalling experiences). Our data suggest that participating in qualitative sexual health research focused on sexual orientation, sexual attraction, and early same-sex sexual experiences may result in minimal harms for YBMSM and multiple benefits, including feeling more comfortable than in a general medical visit.

Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) and Endolysosomal Two-pore Channels Modulate Membrane Excitability and Stimulus-Secretion Coupling in Mouse Pancreatic ß Cells.

Pancreatic ß cells are electrically excitable and respond to elevated glucose concentrations with bursts of Ca(2+) action potentials due to the activation of voltage-dependent Ca(2+) channels (VDCCs), which leads to the exocytosis of insulin granules. We have examined the possible role of nicotinic acid adenine dinucleotide phosphate (NAADP)-mediated Ca(2+) release from intracellular stores during stimulus-secretion coupling in primary mouse pancreatic ß cells. NAADP-regulated Ca(2+) release channels, likely two-pore channels (TPCs), have recently been shown to be a major mechanism for mobilizing Ca(2+) from the endolysosomal system, resulting in localized Ca(2+) signals. We show here that NAADP-mediated Ca(2+) release from endolysosomal Ca(2+) stores activates inward membrane currents and depolarizes the ß cell to the threshold for VDCC activation and thereby contributes to glucose-evoked depolarization of the membrane potential during stimulus-response coupling. Selective pharmacological inhibition of NAADP-evoked Ca(2+) release or genetic ablation of endolysosomal TPC1 or TPC2 channels attenuates glucose- and sulfonylurea-induced membrane currents, depolarization, cytoplasmic Ca(2+) signals, and insulin secretion. Our findings implicate NAADP-evoked Ca(2+) release from acidic Ca(2+) storage organelles in stimulus-secretion coupling in ß cells.

Ca2+ dialogue between acidic vesicles and ER.

Extracellular stimuli evoke the synthesis of intracellular second messengers, several of which couple to the release of Ca(2+)from Ca(2+)-storing organelles via activation of cognate organellar Ca(2+)-channel complexes. The archetype is the inositol 1,4,5-trisphosphate (IP3) and IP3receptor (IP3R) on the endoplasmic reticulum (ER). A less understood, parallel Ca(2+)signalling cascade is that involving the messenger nicotinic acid adenine dinucleotide phosphate (NAADP) that couples to Ca(2+)release from acidic Ca(2+)stores [e.g. endo-lysosomes, secretory vesicles, lysosome-related organelles (LROs)]. NAADP-induced Ca(2+)release absolutely requires organellar TPCs (two-pore channels). This review discusses how ER and acidic Ca(2+)stores physically and functionally interact to generate and shape global and local Ca(2+)signals, with particular emphasis on the two-way dialogue between these two organelles.

Altered distribution and function of natural killer cells in murine and human Niemann-Pick disease type C1.

Niemann-Pick type C (NPC) is a neurodegenerative lysosomal storage disorder caused by defects in the lysosomal proteins NPC1 or NPC2. NPC cells are characterized by reduced lysosomal calcium levels and impaired sphingosine transport from lysosomes. Natural killer (NK) cells kill virally infected/transformed cells via degranulation of lysosome-related organelles. Their trafficking from lymphoid tissues into the circulation is dependent on sphingosine-1-phosphate (S1P) gradients, sensed by S1P receptor 5 (S1P5). We hypothesized that NK-cell function and trafficking could be affected in NPC disease due to the combined effects of the lysosomal calcium defect and sphingosine storage. In an NPC1 mouse model, we found the frequency of NK cells was altered and phenocopied S1P5-deficient mice, consistent with defects in S1P levels. NK cells from NPC1 mice also had a defect in cytotoxicity due to a failure in degranulation of cytotoxic granules, which was associated with reduced lysosomal calcium levels. Affected NPC1 patients and NPC1 heterozygote carriers had reduced NK-cell numbers in their blood and showed similar phenotypic and developmental changes to those observed in the NPC1 mouse. These findings highlight the effects of lysosomal storage on the peripheral immune system.

Two-pore channels (TPCs): current controversies.

Much excitement surrounded the proposal that a family of endo-lysosomal channels, the two-pore channels (TPCs) were the long sought after targets of the Ca(2+) -mobilising messenger, nicotinic acid adenine dinucleotide phosphate (NAADP). However, the role of TPCs in NAADP signalling may be more complex than originally envisaged. First, NAADP may not bind directly to TPCs but via an accessory protein. Second, two papers recently challenged the notion that TPCs are NAADP-regulated Ca(2+) channels by suggesting that they are highly selective Na(+) channels regulated by the lipid phosphatidylinositol 3,5-bisphosphate and by ATP. This paper aims critically to evaluate the evidence for TPCs as NAADP targets and to discuss how the new findings fit in with what we know about endo-lysosomal Ca(2+) stores.